The 31 year old has not played since 2012, but has been given the chance to resurrect his career with a two year deal
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Celtic have failed in a bid to sign Wolves striker Leigh Griffiths.
Griffiths has fallen out of favour with Wolves manager Kenny Jackett in recent weeks but Celtic will have to offer more for the Scotland striker.
A post on Wolves' official Twitter account read: "Kenny has confirmed that Celtic have made a bid for Leigh Griffiths which has been rejected. Striker remains in squad for Oldham game."
Neil Lennon looks chuffed with the Celtic bobble hat Santa brought him on Christmas Day.